The present invention is directed to an expansion dowel and an expansion dowel setting tool where the expansion dowel has a cylindrically-shaped outside surface and the expansion dowel setting tool is formed of a handle part and a striking or driving part.
Expansion dowels of the type including the present invention have an expansion sleeve with an anchoring region which can be expanded by an expansion element. The outside surface of the expansion dowel is substantially cylindrical so that the sleeve forming the dowel, which may profiled surfaces thereon, is basically a cylinder.
Expansion dowels of the type disclosed herein are used in particular for high quality attachments. Accordingly, such expansion dowels are formed of metal and have a load engagement means, for instance in the form of a thread, in the trailing end region of the sleeve. For the most part, the leading or anchoring end region of the expansion dowel is provided with slots open at the leading end. The expansion element can be in the shape of a cylinder or a cone and cooperates with a bore in the expansion sleeve which tapers inwardly toward the leading end, whereby an axial displacement of the expansion element towards the leading end expands the sleeve in the anchoring region.
To achieve a high quality attachment of the expansion dowel of the type disclosed herein, an adequate installation safety margin is important. Such a safety margin is attained if it is assured that an optimum expansion in the anchoring region is achieved. Such optimum expansion depends upon the travel of the expansion element. This travel of the expansion element assures the installation safety margin of the dowel and depends on the arrangement of the expansion dowel.
It is known to utilize expansion dowel setting tools for expanding the dowel, that is, for driving the expansion element. These expansion dowel setting tools have a handle with a striking or driving part. The striking part transmits the force produced by hammer blows to the expansion element. To assure that the expansion element is moved through the distance required for the respective expansion dowel, the striking part of the known expansion setting tools has a shoulder arranged to abut the trailing end face of the expansion dowel for limiting the axial travel of the expansion element. After the shoulder bears against the trailing end face of the expansion dowel it is assured that the expansion element has been displaced through the required travel distance for the respective expansion dowel whereby the required installation margin of safety is achieved affording the correct expansion of the dowel.
Since, as already mentioned, the movement or displacement of the expansion element is a function of the design of the expansion dowel, for instance its dimensions, it is necessary to provide a special expansion dowel setting tool for each type of expansion dowel to be used to assure the proper expansion required for the appropriate installation margin of safety. Due to the problem arising from the great number of the required expansion dowel setting tools, there is the possibility that an incorrect expansion dowel setting tool, not matching the corresponding expansion dowel, may be used. The consequence of such an improper combination is an insufficient or excessive expansion whereby the required installation margin safety is not attained.